A £7billion high-speed rail link between Manchester and Leeds - HS3 - would help create a "northern powerhouse" to complement not rival London as Britain's global city, George Osborne insisted.

But as the Chancellor also held out the promise of "serious devolution of powers and budgets" to cities in northern England in return for adopting elected mayors with powers similar to those enjoyed by Boris Johnson in London, political opponents suggested this was more about electoral politics than anything else given Conservatives fear they could do badly in northern English seats in the 2015 General Election.

It was only three years ago that the idea of elected mayors was soundly rebuffed when the residents of nine major cities rejected it in several referendums.

"This is more about northern votes than northern growth," declared Lord Prescott.

The former Labour Deputy Prime Minister pointed out Mr Osborne's remarks echoed the Northern Way initiative, which the Labour peer launched in 2004 to drive growth and improve connections across the region but which was later scrapped by the Lib-Con Coalition.

"There's no money, just a declaration from the very same man who abolished the Northern Way three years ago. He is trying to reverse his own damaging decision and we haven't seen any detail because there isn't any detail," added Lord Prescott.

Gordon MacDonald, the SNP MSP, said it was ridiculous the UK Government was considering extending high-speed rail without any regard to Scotland.

"What has become clear is that with a No vote the Tory-led Westminster system will keep Scotland in the slow lane," he said, stressing: "There is an undeniable economic case to connect Scotland to the rest of the UK and the continent."

In April, Alex Salmond announced he was establishing a feasibility study to look at starting a high-speed rail link from Scotland to England, saying the UK Government's £43bn HS2 plans "lacked high ambition". Speaking at Manchester's Museum of Science and Technology, the Chancellor noted that within 40 miles' commuting distance of the venue were cities that were home to a total of 10m people - more than Tokyo, London or New York - with important industries, great universities and areas of natural beauty.

But, he explained, it was quicker to travel by train from London to Paris than to cross half the distance between Liverpool and Hull.

The Conservative aim was to create a "radical transport plan", so that travelling between England's northern cities felt like travelling "within one big city".

Mr Osborne, who represents Tatton in Cheshire, told his audience: "The cities of the north are individually strong but collectively not strong enough; the whole is less than the sum of its parts.

"So the powerhouse of London dominates more and more and that's not healthy for our economy; it's not good for our country. We need a northern powerhouse too. Not one city but a collection of northern cities; sufficiently close to each other that, combined, they can take on the world."

Speaking during a later visit to a Coca-Cola plant in Wakefield, Prime Minister David Cameron said the creation of a northern powerhouse was an "exciting vision", noting: "This is an attempt to say - let's make the most of our great northern cities so we get growth right across our economy."

Earlier this year, the First Minister spoke about London becoming the "dark star", drawing jobs and investment to itself to the detriment of the rest of the country, and suggested the answer was the creation of a "northern light" in the form of an independent Scotland to rebalance the economy across the whole of the British Isles.